Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 182336 AAA

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
636 PM CDT Fri May 18 2018

.DISCUSSION...Updated for latest aviation discussion below.


.AVIATION...Low pressure moving into the Plains State tonight is
maintaining a moderately strong low level wind flow which will
increase the low level moisture. Surface inversion strengthens
overnight with stratus forming at and below the base of the
inversion (1300-1800 feet). Models suggest this MVFR ceiling to
form anywhere between 03-06Z and persist intermittently through at
least 15Z Saturday. VFR conditions redevelop mid to late morning
Saturday and last through the afternoon hours. Wind to remain
elevated this evening and much of the night with gusts becoming
less frequent after midnight. Southeast wind and stronger gusts
increase once again mid to late morning Saturday. Areas of haze
due to localized controlled burning were impacting some surface
visibilities early in the afternoon. Some of this haze/smoke could
settle to the surface and get trapped underneath the inversion
tonight and Saturday with some slantwise visibilities (not surface
vsby) being restricted on approach to KBRO and possibly at KHRL
between 4 to 7 miles.


.PREV DISCUSSION... /issued 247 PM CDT Fri May 18 2018/

SHORT TERM (Now through Saturday night): The heat continues
today as ridging remains dominant across south Texas. Southerly
flow has increased today as low pressure builds in Kansas. Winds
will stay elevated overnight with the low slowly moving across
Kansas, with Gulf moisture slowly increasing through the night,
noted by dewpoints jumping above 70 for all areas. With the added
moisture in the region tomorrow, along with a midlevel wave moving
across the Panhandle, will likely see more cloud cover tomorrow,
and a small chance for a streamer shower developing right along
the coast late Saturday night. Increased moisture will also mean
slightly lower temps tomorrow, but this will be offset by the
moisture bringing heat index values again to around 100.

LONG TERM (Sunday through Friday): Initialized with the superblend,
and made only minor adjustments to high temperatures to reflect the
ongoing warmer weather. Mid level ridging will remain an important
feature in the long term, though the position will shift back and
forth, east and west, based on the influence of upstream forcing.
Ridging will be over the west Gulf on Sunday, over high pressure, as
a negative tilt trough lies over the southwest United States. It is
during this time and through Monday that a weak mid level low and
surface reflection develop over the northeast Gulf. This feature
will bear watching. In addition, upper energy does make it a little
farther south than the Big Bend Sunday night, and will still carry
isolated thunderstorms for the Upper Valley at that time. A large,
mid level low over the Southwest will spawn short waves moving
southwest to northeast across New Mexico from late this weekend
through the middle of next week, but mid level ridging over the
northwest Gulf will hold steady, and limited instability will be
able to work across Mexico into the regions west of the CWA. In
fact, as the low begins to weaken during the middle of next week,
ridging over the local area will rebuild, though a brief pulse of
convection may flare up over the Big bend Thursday night.

In the mean time, high pressure will remain in control at the
surface, supporting continued onshore winds, breezy at times
Saturday and Sunday in response to a tighter gradient with Plains
lower pressure. Temperatures will continue an above normal trend. A
sea breeze may develop on Sunday, with short wave energy moving
through the upper flow Sunday night, kicking off isolated convection
to the west of the CWA, which could drift east into the upper valley
overnight. That will be the main potential for rain in this long
term. Modest ridging will remain overhead or just east over the
northwest Gulf, lending broad stability to the weather for much of
the long term. Warmer than average temperatures, especially by
day, moderate southeast winds, and mostly sunny skies will mark
most of the long term.

Now through Saturday night: Small Craft Advisories are in effect
for the Laguna Madre through sunset for winds right around 20
knots. Winds will relax after sunset, but will likely still remain
around or just above 15kts. Winds across the open Gulf waters will
rise to near 20 knots by midnight, so Advisories will need to be
hoisted there later this evening. Breezes continue into the day
Saturday, with winds again reaching 20 knots across the Laguna

Sunday through Wednesday night: Increased winds supporting small
craft should exercise caution to low end small craft advisory
conditions, along with elevated seas, will persist into Sunday and
Sunday night, and possibly Monday, on the Gulf. The gradient will
then relax and moderate wind and sea conditions will return for
the Monday to Wednesday night interval.


BAYVIEW/PORT ISABEL  77  92  78  90 /   0   0  10  10
BROWNSVILLE          77  93  77  92 /   0   0  10  10
HARLINGEN            75  96  76  94 /   0   0  10  10
MCALLEN              76  98  77  95 /   0   0  10  10
RIO GRANDE CITY      74 100  76  97 /   0   0   0  10
SOUTH PADRE ISLAND   78  85  78  84 /   0   0  10  10


GM...Small Craft Advisory for winds until 7 PM CDT this evening for

     Small Craft Advisory until 10 AM CDT Saturday for GMZ150-155-170-



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